Rebuilding front brake calipers - Audi Allroad

[skuncan]

Wow... :shock:

Never really expected so much info... but thanks to all so far.. its very interesting to hear a lot of different peoples views..

Just to be clear... i can change the pads and discs if needed with no issues.. having done it on the car a couple of times already...

really for me it is about the front calipers needing a rebuild
(in my view of them currently)

So it seems the options are;

leave them alone ?
get a used set and rebuild and fit ?
rebuild current set ?

thanks
D

 

[NAILTRAIL96]

My experience of mechanics with electronic controls and sensors is that if it isn't broken.....

 

[unkleGsif]

My experience of mechanics with electronic controls and sensors is that if it isn't broken.....

..... take it apart and see how it works?



G

 

[drcarlos]

Wow... :shock:

Never really expected so much info... but thanks to all so far.. its very interesting to hear a lot of different peoples views..

Just to be clear... i can change the pads and discs if needed with no issues.. having done it on the car a couple of times already...

really for me it is about the front calipers needing a rebuild
(in my view of them currently)

So it seems the options are;

leave them alone ?
get a used set and rebuild and fit ?
rebuild current set ?

thanks
D

For what it's worth, i'd have a go. I have rebuilt the half brake calliper I use as a clutch actuator on my racing lawnmower, it took about 15 minutes (bearing in mind it was corroded just had a damaged seal that needed replacing) and it was really hard, so changing a couple of seals an O-ring and cleaning the piston up shouldn't be too hard.

I'm not jumping on one or other side of this - apart from to say, sometimes theoritical good practise is often spurned these days, in favour of whatever "just works" - as pragmatism rules over the probably small likelihood of problems by not adhering to what is probably the best way(s) of doing things - well that and the fact that people have psyhcological investment in their approach and ways of doing things.

Some of my older relatives (now sadly gone) often lamented how in work situations, the "proper" way of doing mechanical or engineering tasks, has deteriorated to little if any adherence over time.

(most ABS faults are caused by faulty wheel sensors and I've never had an ABS fault at all).

My only real response is to that - I've encountered ABS problems from sensors / reluctor rings, from loom wiring to the sensor(s) - but in my experience, an equal, if not greater incidence of ABS ECU issues.

That could possibly be a result of car choice, but for me it's even stevens - one situation was wiring / sensor related (actually the wiring that joined the rear part of the loom) the other the ABS ECU. When I used to read / participate in car forums, I read plenty of people playing about with wiring, sensors and reluctor rings, but mainly, it was an ABS ECU issue.

I guess I agree with you Neil (not many do ) and would fall on the side of ABS faults mainly being electrical related (I was too engrossed in my opinions about the FUD to elaborate any further on that side of things).

Also I am necessarily saying it's a bad thing not to open the bleed nipple and you shouldn't do things this way. It's the way it's being presented to put people off from doing a simple hours job themselves.
Mention bleeding brakes to most people and it would be enough for them to say 'sod it i'll just get the garage to do it'.
The mechanics that I know (and I know a few due to racing) don't open bleed nipples they just compress or screw the piston back in anyway so in fact what you thought you couldn't do they have done anyway and the garage has made a nice profit on an already over inflated hourly rate.

Carl.

 

[unkleGsif]

the common sense approach to the bleed nipple issue (in my view and experience at least) is that if you DONT do it, then when pumping the piston back into the caliper, the level in the resovoir wil rise, and that by doing 4 pistons, it is likely to rise just that little bit further than the top of the resovoir...... especially if you are under the car, and the resovoir is up there in t he engine bay

= brake fluid down the front bulkhead :shock:
= rust in 6 months

with a small pipe on the bleed nipple, its easy to control the fluid coming out into a bottle, and if you are carefull, there is little chance of introducing air into the system


G

 

[drcarlos]

the common sense approach to the bleed nipple issue (in my view and experience at least) is that if you DONT do it, then when pumping the piston back into the caliper, the level in the resovoir wil rise, and that by doing 4 pistons, it is likely to rise just that little bit further than the top of the resovoir...... especially if you are under the car, and the resovoir is up there in t he engine bay

= brake fluid down the front bulkhead :shock:
= rust in 6 months

with a small pipe on the bleed nipple, its easy to control the fluid coming out into a bottle, and if you are carefull, there is little chance of introducing air into the system


G

This is not right, if the fluid is filled to the Max level with new pads in it will get to min level when the fronts need replacement and will throw on a warning light.
What happened to you, also happened to me by a shonky dealer who instead of swapping the pads (and they got down to nearly metal before I noticed because of it) just topped up the sodding fluid to put the light out. Cue an overflow when piston compressed.

Little chance? You really want to take any chance on something a important as brakes?
Remember you are opening a closed system at the end that should remain closed apart from when being bled.

Carl.

 

[unkleGsif]

There was no shonky spanner monkey involved. It was me.
It is common, no, "standard" practice to top up fluid. When doing ALL 4 pistons, I BET you the fuid will rise at least to the top of the resovoir... unless its too low to beging with

I didnt say anything about taking a chance. I said there was little chance of introducing air into the system :roll:

Again, common sense would dictate that if this WERE to happen, then the system would be bled

G

 

[Neil]

I guess I agree with you Neil (not many do )

It's an exclusive club, doncha know!

Also I am necessarily saying it's a bad thing not to open the bleed nipple and you shouldn't do things this way. It's the way it's being presented to put people off from doing a simple hours job themselves.
Mention bleeding brakes to most people and it would be enough for them to say 'sod it i'll just get the garage to do it'.
The mechanics that I know (and I know a few due to racing) don't open bleed nipples they just compress or screw the piston back in anyway so in fact what you thought you couldn't do they have done anyway and the garage has made a nice profit on an already over inflated hourly rate.

Carl.

Just regarding the "get the garage to do it" and bleed nipples on brake calipers - some garages are loath to touch them - because as has been suggested, in many cases they've been in an exposed environment for years, and never touched - and can be siezed and snap / shear when garages try to undo them - leaving them in an awkward position with customers who just consider it the garage's fault and inflating prices for work.

I'd agree, too - there's an increasing amount of stuff that the enthusiastic amateur is being discouraged from doing on cars - some new fangled horse-less carriages have to have somewhizbang, computerised gadget just to do things like retract calipers, and reset their positions.

 

[old_coyote_pedaller]

Opening the bleed nipple won't require the brakes to be bled unless the brake pedal has been pressed and released with the nipple open allowing air to be drawn in.
If you don't do this how is the air going to get in? For air to get in fluid must come out for the air to replace it in system. Crack open the bleed nipple and you will find that fluid weeps out, the weight of the fluid in the pipes above caliper pushing it out, leave it open and you will soon have an empty fluid reservoir. How do I know that?

The method I have used to push pistons back is this,
fit ring spanner over nipple,
put clear plastic hose onto nipple with end of hose in a container to catch spillage,
ensure hose goes up in a loop before entering the container as this keeps fluid in plastic pipe above nipple,
then as you push the piston back, open the nipple, the fluid will be pushed out as piston moves in,
keep pressure on piston as you then close nipple.
Do the same with other pistons as required then fit the pads, remember to top up fluid reservoir with new fluid when all pads are fitted as the level will have dropped as old pads wore down.

 

[unkleGsif]

Opening the bleed nipple won't require the brakes to be bled unless the brake pedal has been pressed and released with the nipple open allowing air to be drawn in.
If you don't do this how is the air going to get in? For air to get in fluid must come out for the air to replace it in system. Crack open the bleed nipple and you will find that fluid weeps out, the weight of the fluid in the pipes above caliper pushing it out, leave it open and you will soon have an empty fluid reservoir. How do I know that?.....

tis true. And with the cap on the resovoir, its like a thumb over the end of a straw filled with water

G